Digital telephony devices, including digital switches, digital PBXs (private branch exchanges) and digital telephones, are well known. In a typical installation of a digital PBX, various kinds of digital telephony equipment may be connected to the PBX. These kinds of digital telephony equipment may include telephones and other devices, such as a voice mail system, an interactive voice response unit (IVRU), and/or telephone emulators. In other cases, digital switch emulators may be connected to digital telephones. The signals exchanged between two pieces of digital telephony equipment are typically serial signals. These signals may be entirely or partially scrambled according to various scrambling algorithms in order to prevent long sequences of zeros or ones, and/or to help provide confidentiality for the signals. The scrambling algorithms used by manufacturers of digital telephony equipment often vary from manufacturer to manufacturer. It can therefore be difficult and/or costly to provide digital telephony equipment that is compatible with the equipment of many different manufacturers.